1. Field of Invention
The present invention relates to the technical field of water tank parts of a flush toilet, and more particularly to a flush valve assembly structure installed in a water tank and capable of adjusting a flush water volume conveniently.
2. Related Art
According to flush toilet standards in different countries, it is desired a flush toilet may reduce the flush water volume each time in the flushing operation to save water and protect the environment. Therefore, in current flush toilet designs, mostly the flushing intensity is increased and the flushing time is reduced, so as to ensure that the toilet bowl may be cleansed while satisfying the spirit of environmental protection. Normally, a common design is to install a flush valve assembly on a bottom of a water tank.
US Patent No. 20070101485A1 entitled “CANISTER FLUSH VALVE” has disclosed such a structure. The flush valve assembly is normally fixed on a bottom of a water tank by a valve seat. In a normal state, the flush valve assembly blocks and seals a tank outlet on the bottom of the water tank and linking the water tank and a toilet bowl, so as to form a closed space for storing clean flush water in the water tank. When an operator pulls a trip lever, or presses a flush button, a canister flush valve on the flush valve assembly is lifted to be separated from the valve seat, so as to form a valve port through which the flush water flow in the water tank flushes the toilet bowl. In a later period of the flushing process, the flush water in the water tank reduces to a lower level, so the flush valve may be opened, and the valve port is closed. Then, the water is supplemented to prepare for the next flushing.
In a current flush valve assembly, a through hole is arranged in a bottom of the canister flush valve. When the valve port is opened and most of the flush water flows to the toilet bowl, a small amount of water flows into the canister flush valve from the through hole, and accumulates in a chamber between an outer cylindrical wall and an inner cylindrical wall. Thus, the accumulated flush water increases the weight of the canister flush valve, so the canister flush valve may drop more rapidly, and the valve port is closed at a higher speed. Thus, the flush water volume used each time is reduced. However, the standards for the flush water volume used each time of the flush toilet are different in different countries, so the design that the flush water flows into the canister flush valve to increase the weight of the canister valve cannot meet the standards specified in all countries. Therefore, it is necessary to develop other designs that may increase the weight of the canister valve, so as to change the speed of closing the valve port and change the flush water volume used each time.
In addition, for water tanks of different sizes, as the capacities of the water stored in the water tanks are different, the speeds of closing the valve ports are also different. Therefore, the application lacks flexibility, and the speed for closing the valve port and the flush water volume used each time cannot be adjusted flexibly for different conditions. Thus, it is necessary to further design a flush valve assembly structure that may adjust the flush water volume conveniently.
Further, in a current flush valve assembly, the canister flush valve is often sleeved on a guide rod, and a guide edge on the guide rod is used to guide the canister flush valve, such that the canister flush valve may be lifted up and return to the original position smoothly each time. However, in the existing guide rod design, a top end of the guide edge is approximately at the same level as a bottom edge of an annular wall surface in a round rod shape in a top end segment of the guide rod. Therefore, when the canister flush valve is lifted up, the top edge of the inner cylindrical wall may easily be stuck by a bottom plane at the intersection of the annular wall surface in the round rod shape and the top end of the guide edge, which leads to error operation of the canister flush valve, or influences the smoothness of the flushing operation. These problems also need to be solved.